Rather than being affected by environmental stimuli, sufferers of phobophobia are set off by the internal sensations of fear itself, which is further exacerbated by experiencing those exact same sensations.

Google hits on the term (hits include both with and without the hyphen), a negligible number (compare 1,490,000 for homophobia, 34,900 for phobophobia (fear of fear), 29,200 for heterophobia (fear of heterosexuals), 14,900 for gamophobia